target: Drop se_lun->lun_active for existing percpu lun_ref

With se_port_t and t10_alua_tg_pt_gp_member being absored into se_lun,
there is no need for an extra atomic_t based reference count for PR
ALL_TG_PT=1 and ALUA access state transition.

Go ahead and use the existing percpu se_lun->lun_ref instead, and
convert the two special cases to percpu_ref_tryget_live() to avoid
se_lun if transport_clear_lun_ref() has already been invoked to
shutdown the se_lun.

Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_alua.c b/drivers/target/target_core_alua.c
index 0a0087311cfb33e6b84035421a12bbdcd22c3d86..02d8e1a8a6a520006dc82cf4e68eb33607c70506 100644 (file)
--- a/drivers/target/target_core_alua.c
+++ b/drivers/target/target_core_alua.c
@@ -969,7 +969,8 @@ static void core_alua_do_transition_tg_pt_work(struct work_struct *work)
                 * every I_T nexus other than the I_T nexus on which the SET
                 * TARGET PORT GROUPS command
                 */
-               atomic_inc_mb(&lun->lun_active);
+               if (!percpu_ref_tryget_live(&lun->lun_ref))
+                       continue;
                spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
 
                spin_lock_bh(&lun->lun_deve_lock);
@@ -998,7 +999,7 @@ static void core_alua_do_transition_tg_pt_work(struct work_struct *work)
                spin_unlock_bh(&lun->lun_deve_lock);
 
                spin_lock(&tg_pt_gp->tg_pt_gp_lock);
-               atomic_dec_mb(&lun->lun_active);
+               percpu_ref_put(&lun->lun_ref);
        }
        spin_unlock(&tg_pt_gp->tg_pt_gp_lock);
        /*

diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index 60624bb6c59803a5931c42655e0453334fe52a60..94935eaa7fa7a3a09b32c478ad391e26f46e69d1 100644 (file)
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -704,7 +704,8 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
         */
        spin_lock(&dev->se_port_lock);
        list_for_each_entry_safe(lun_tmp, next, &dev->dev_sep_list, lun_dev_link) {
-               atomic_inc_mb(&lun_tmp->lun_active);
+               if (!percpu_ref_tryget_live(&lun_tmp->lun_ref))
+                       continue;
                spin_unlock(&dev->se_port_lock);
 
                spin_lock_bh(&lun_tmp->lun_deve_lock);
@@ -751,7 +752,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
                        if (ret < 0) {
                                pr_err("core_scsi3_lunacl_depend"
                                                "_item() failed\n");
-                               atomic_dec_mb(&lun->lun_active);
+                               percpu_ref_put(&lun_tmp->lun_ref);
                                kref_put(&deve_tmp->pr_kref, target_pr_kref_release);
                                goto out;
                        }
@@ -770,7 +771,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
                                                deve_tmp->mapped_lun, NULL,
                                                sa_res_key, all_tg_pt, aptpl);
                        if (!pr_reg_atp) {
-                               atomic_dec_mb(&lun_tmp->lun_active);
+                               percpu_ref_put(&lun_tmp->lun_ref);
                                core_scsi3_lunacl_undepend_item(deve_tmp);
                                goto out;
                        }
@@ -782,7 +783,7 @@ static struct t10_pr_registration *__core_scsi3_alloc_registration(
                spin_unlock_bh(&lun_tmp->lun_deve_lock);
 
                spin_lock(&dev->se_port_lock);
-               atomic_dec_mb(&lun_tmp->lun_active);
+               percpu_ref_put(&lun_tmp->lun_ref);
        }
        spin_unlock(&dev->se_port_lock);
 

diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c
index 5b30940ccaf21760293384490f2c4218878fcce4..b9fcf2c4898ea023252a3a9e4f0f720ad8e1c5fe 100644 (file)
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -607,7 +607,6 @@ struct se_lun *core_tpg_alloc_lun(
        mutex_init(&lun->lun_tg_pt_md_mutex);
        INIT_LIST_HEAD(&lun->lun_tg_pt_gp_link);
        spin_lock_init(&lun->lun_tg_pt_gp_lock);
-       atomic_set(&lun->lun_active, 0);
        lun->lun_tpg = tpg;
 
        return lun;
@@ -667,13 +666,16 @@ void core_tpg_remove_lun(
        struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev);
 
        core_clear_lun_from_tpg(lun, tpg);
+       /*
+        * Wait for any active I/O references to percpu se_lun->lun_ref to
+        * be released.  Also, se_lun->lun_ref is now used by PR and ALUA
+        * logic when referencing a remote target port during ALL_TGT_PT=1
+        * and generating UNIT_ATTENTIONs for ALUA access state transition.
+        */
        transport_clear_lun_ref(lun);
 
        mutex_lock(&tpg->tpg_lun_mutex);
        if (lun->lun_se_dev) {
-               while (atomic_read(&lun->lun_active))
-                       cpu_relax();
-
                target_detach_tg_pt_gp(lun);
 
                spin_lock(&dev->se_port_lock);

diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index b82a989a4d3bf86765bc43bc7521043654b78dbd..eefc2b0cfaa3a614cd60bd40cb03297101e6929b 100644 (file)
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -721,7 +721,6 @@ struct se_lun {
        struct t10_alua_tg_pt_gp *lun_tg_pt_gp;
        spinlock_t              lun_tg_pt_gp_lock;
 
-       atomic_t                lun_active;
        struct se_portal_group  *lun_tpg;
        struct scsi_port_stats  lun_stats;
        struct config_group     lun_group;